Besides the integration of electronic circuits, technological advancement has also led to miniaturization of mechanical components and systems. What are referred to as microelectromechanical systems (MEMS) realize mechanical units in the range of a few micrometers and less. In so doing, industrial production makes use of a multilayer construction, often falling back on materials from the semiconductor industry. In this context, cavities are formed in which micromechanical structures may be disposed. Moreover, as a rule, upper layers are provided which enclose the mechanical structure in the cavity in which a well-defined environment may be created. For this, a suitable liquid or gaseous fluid is introduced into the cavity through openings, and the openings are sealed. With that, the cavity is also protected from external influences, and an unwanted change over time such as corrosion is prevented. Therefore, there is a requirement to seal the openings, and accordingly, to permanently enclose a fluid in the cavity.
Known methods enclose a fluid whose pressure and density are often unable to substantially influence the mechanical properties of the mechanical structure.
Moreover, in conventional methods, sealing material and sometimes also aggressive components penetrate into the cavity, where they can then lead to damage. For example, to seal off a mechanical structure in a cavity, EP 1274648 B1 discusses the closure of openings by a “refill process.” In that case, remaining openings in the substrate are plugged, and an internal pressure or an internal atmosphere, which are determined by the process conditions of the refill process, is trapped in the cavity. The containment of a specific internal atmosphere decoupled from this process is not possible. Furthermore, sealing material, components thereof or perhaps reaction products are able to penetrate into the cavity.